BillJx said:
Andre, the conclusions of experts are at your fingertips.
http://en.wikipedia.org/wiki/Geothermal_(geology )
http://www.physorg.com/news62952904.html
http://www.physlink.com/News/121103PotassiumCore.cfm
http://www.newscientist.com/article.ns?id=mg18725103.700
Of course, there are minority opinions.
http://www.nov55.com/heat.html
With respect I really think you've misunderstood what the "experts" have said. I browsed through your references and I couldn't find anything that explicitly states that "fission of uranium contributes substantially" to the core's heating. Actually most of the Uranium is thought to be in the lower mantle and a fair bit is in the crust, of course it does do a lot of heating, but it doesn't heat the core, which was the original question!
One article mentions that there could be K in the core, which is a radiogenic element, this might well be true and I have found a (slightly more reputable) source which backs this up:
The fact that the core is largely composed of Fe was
firmly established as a result of Birch’s (1952) analysis
of mass-density/sound-wave velocity systematics. Today
we believe that the outer core is about 6–10% less
dense than pure liquid Fe, while the solid inner-core
is a few percent less dense than crystalline Fe (e.g.
Poirier, 1994a). From cosmochemical and other considerations,
it has been suggested (e.g. Poirier, 1994b;
Allègre et al., 1995; McDonough and Sun, 1995) that
the alloying elements in the core might include S, O,
Si, H and C. It is also probable that the core contains
minor amounts of other elements, such as Ni and K.
(Vocadlo et al. 2003)
The newscientist article you referenced makes the distinction that the antineutrinos are coming from within the core, however I fail to see how they can be sure that these antineutrinos are not coming from the lower mantle - or even the continental crust! I suspect this is a sloppy article and without seeing a more robust source I will consider it to be incorrect.
Anyway, the fact is the experts do not think that there is a significant U source in the core. If there were, how would you explain that the average density of the core is observed to be ~3% less than that of iron (at the appropriate pressures)? Also, how would the inner core be cooling if there were U constantly heating it up? These are big problems for your theory which - as I have stated - is a theory with little backing from the experts.